A known valve timing adjusting apparatus includes a housing, which is rotated integrally with a crankshaft of an internal combustion engine, and a vane rotor, which is rotated integrally with a camshaft. Such a valve timing adjusting apparatus adjusts valve timing of intake valves or exhaust valves by changing a rotational phase of the vane rotor relative to the housing. The rotational phase of the vane rotor is changed by supplying working oil to advancing chambers or retarding chambers defined in the housing. For example, JP2005-351182A discloses a vane rotor that includes a plurality of metal plates, which are stacked one after another in an axial direction.
The inventor of the present application has proposed to place an oil pressure control valve, which supplies working oil to the advancing chambers or the retarding chambers, in a center portion of the vane rotor that has the laminated portion made of the metal plates. In such a case, an inner peripheral wall surface of the vane rotor seals between corresponding adjacent ports of a sleeve of the oil control valve.
However, an inner diameter of the vane rotor tends to vary from product to product due to, for example, displacement of the metal plates relative to each other. Thus, it is required to set a relatively large clearance between the inner peripheral wall surface of the vane rotor and an outer peripheral wall surface of the sleeve to enable insertion of the sleeve into the vane rotor. Therefore, a sealing performance for sealing between the ports of the sleeve may possibly be deteriorated to cause an increase in leakage between the ports of the sleeve. The increase in the leakage between the ports of the sleeve may cause deterioration in an operational speed of the vane rotor and deterioration in a holding performance for holding the rotational phase of the vane rotor relative to the housing.